THE TRAVEL-INDUCED CARBON FOOTPRINT OF PRIOR ECPR GENERAL CONFERENCES

Although total conference emissions include other aspects (e.g., heating and electricity in hotels and conference venues and the carbon footprint of onsite catering), those resulting from traveling comprise the lion’s share of the total GHG emissions. A study of a virtual-reality online conference in the United States showed that if it had taken place physically, the travel-induced footprint would have been 7,188 tons of CO₂ compared to only 524 tons for electricity and heating (Balanzat Reference Balanzat2020). It thus is reasonable to concentrate primarily on the travel-induced emissions when the goal is to reduce the overall carbon footprint of conferences.

To estimate the travel-induced carbon footprint, I followed the same strategy as described in Jäckle (Reference Jäckle2019, 634–38). The basic idea is simple: I multiplied the distance (in kilometers) that participants travel from their home institution to the conference venue by the GHG emissions produced per passenger-kilometer (dependent on the means of transportation used). This determines the amount of CO₂-eq of each participant.Footnote ¹ However, I applied updated emission factors for the three means of transportation considered in the Jäckle (Reference Jäckle2019) study: airplane, long-distance coach, and train.Footnote ² The current study uses four different sources (table 1). Every organization that publishes emission factors makes assumptions regarding the GHG emissions of different means of transportation (e.g., the average passenger-load factor and the electricity mix to power trains). Thus, to derive a minimum-to-maximum interval of possible carbon footprints for the conferences, it makes sense not to use a single but rather a range of different sources.

Table 1

Emission Factors in Grams CO₂-eq per Passenger-Kilometer

Notes: UBA: Umweltbundesamt (German Federal Environmental Agency) Transport Emission Model (TREMOD) 6.03, 2018 (Allekotte et al. Reference Allekotte, Biemann, Heidt, Colson and Knörr2020); EEA: European Environment Agency Transport and Environment Reporting Mechanism (TERM) report (2014); UK: Government of the United Kingdom conversion factors (UK Department for Business, Energy & Industrial Strategy 2021); NTM: Network for Transport Measures (2018). *EU average electricity/EU green electricity; **long haul to/from the United Kingdom in economy class/business class/first class; ***regional (<785km)/continental (785–3,600km)/intercontinental (>3,600km); radiative forcing index=2.0.

Aware of the affiliations and thus the home institutions of participants,Footnote ³ I calculated the travel distances by airplane, by coach, and by train. Finally, I assumed that all participants, who can travel from their home institution to the conference location within 5 hours by coach, traveled land-bound (i.e., by either long-distance coach or train). If land-bound travel took longer, I assumed that participants traveled by airplane. Based on this assumption, I calculated eight versions of the travel-induced carbon footprint dependent on the means of land-bound transportation (i.e., coach or train) and the four sources of emission factors. Figure 1 depicts the resulting minimum-to-maximum range. Whereas the 2015 conference that took place in Montreal clearly stands out, all other conferences also accounted for travel-induced carbon emissions between approximately 900 and 2,300 tons of CO₂-eq. This means that the 1,500 to 1,900 attendees produced about the same amount of GHG simply by traveling to the conferences as 120 to 320 average UK citizens produced throughout all of 2018.Footnote ⁴

Figure 1

Total Travel-Induced GHG Emissions of ECPR General Conferences 2013–2019

Notes: Journeys <5 hours travel time: by long-distance coach or train; >5 hours: by airplane. Range of estimations due to differences in the four emission factors (see table 1).

On average, each participant at one of the Europe-based conferences emitted between 500 and 1,400 kg CO₂-eq, which is about as much as an average human would emit within an entire year by 2040 to effectively reduce global warming by 1.5 degrees compared to the preindustrial age (Institute for Global Environmental Strategies 2019). Furthermore, GHG emissions from traveling are unevenly distributed among the participants: for example, at the Hamburg ECPR GC, only 7% of the participants accounted for 50% of the total travel-induced emissions. Thus, giving especially those traveling to the conferences from far away the option of joining virtually could significantly reduce the overall carbon footprint.

COMPARING THE CARBON FOOTPRINT OF A VIRTUAL GC TO A PHYSICAL EVENT

To estimate the effects of switching the 2020 GC to a virtual event on its carbon footprint, I first calculated the emissions necessary for hosting it and then compared it to the hypothetical case, if all participants of the online conference had traveled to the originally planned venue (i.e., Innsbruck, Austria). For an online conference, GHG emissions can be attributed primarily to the electricity consumption of the event, mainly generated by two factors: (1) the electricity needed to power the participants’ devices; and (2) the electricity needed for servers providing video and audio transfers. The virtual ECPR GC took place from August 24 to 28, 2020. It was possible to attend a maximum of about 40 hours of online activities (including panels and roundtables as well as refreshers, pauses, virtual social gatherings, and online fitness exercises). Making several assumptions, it is possible to calculate a range for the overall electricity consumption of participants’ devices using the following formula:

$$ {EC}_{devices}=P\times A\times D\times EU $$

where EC_devices = total electricity consumption of all participants’ devices for the overall conference in kWh; P = number of participants; A = attendance rate; D = total duration of conference in hours; and EU = electricity usage of devices in W.

Similarly, the electricity consumption of video and audio data transfers on the internet can be estimated, assuming the upload and download data usage for 1 hour on the streaming platform (i.e., Zoom)Footnote ⁵ and the electricity intensity for internet transfersFootnote ⁶ using the following formula:

$$ {EC}_{internet\_ transfer}=P\times A\times D\times U\times I $$

where EC_{internet_transfer} = total electricity consumption of all data transfers in kWh; P = number of participants; A = attendance rate; D = total duration of conference in hours; U = data usage for 1 hour on Zoom; and I = average electricity intensity of internet transfers in kWh/GB.

Varying the overall attendance rate A from 20% to 80% and the electricity usage EU per device from 50 to 200 WFootnote ⁷ results in a range of 880 to 14,100 kWh for powering participants’ devices for the online conference. For the lowest/highest video quality on Zoom, the overall electricity consumption of data transfers is estimated at 215/2,625 kWh. Assuming that most researchers currently use laptops (rather than desktop PCs), select the medium-quality setting of 720p for the video stream, and attend about one third of the time at an online conference (i.e., A = 33%; EU = 70 W; U = 1.35 GB/h), reasonably realistic estimations are 2,050 kWh for the devices and 590 kWh for the internet data transfers.

Using electricity consumption, it is possible to estimate the carbon footprint of the online conference but it depends on the way that the electricity is produced. Data from the European Environmental Agency show that in 2016, producing 1 kWh of electricity in France emitted approximately 58 grams of CO₂, whereas producing the same amount in Poland emitted 773 grams of CO₂ (European Environment Agency 2021). More recent estimates report, for example, 233 grams for the United Kingdom and 402 grams for Germany (UK Department for Business, Energy & Industrial Strategy 2021; Umweltbundesamt 2021). Applying the low French and the high Polish emission factors for the calculation, the resulting estimates can be regarded as the upper and lower bounds of total GHG emissions for this online conference. Table 2 lists these minimum and maximum estimations of the total carbon footprint produced by participants’ devices and internet transfers based on the electricity-usage figures calculated previously, as well as a reasonably realistic estimation (i.e., best est.) using the EU average of 296 g/kWh.

Table 2

Carbon Footprint of the Virtual ECPR GC 2020 Compared to the Physical Event in Innsbruck (in Tons CO₂-eq)

Note: *Journeys <5 hours travel time: by long-distance coach or train.

To compare these estimates for the virtual conference to the hypothetical case, in which the event would have taken place in Innsbruck, table 2 includes those for the carbon footprint of traveling—estimated in the previous way—as well as for local emissions. To calculate the latter onsite emissions, I used the estimation procedure and the electricity and natural-gas usage amounts for hotels and conference buildings reported in Balanzat (Reference Balanzat2020). Assuming a conference venue of approximately 400,000 ft² (37,160 m²), an average hotel room of 330 ft² (30 m²) occupied by two conference attendees, heating by natural gas (gross calorific value: 40.5 MJ/m³; emission factor: 56 tons CO₂/TJ), and applying the comparatively low emission factor for electricity production in Austria (85.1 g/kWh, due to a high share of hydropower), the total electricity- and heating-related carbon footprint at the GC in Innsbruck would have been approximately 32 tons CO₂-eq.

Catering is another factor that increases total emissions at a physical event. The amounts presented for the catering carbon footprint are based on the assumption that participants would have three lunches at the conference venue and one meal at the conference reception. The estimated range of 7 to 48 tons results from potential differences in menus: conventional (American) menus have total lifecycle GHG emissions approximately six to seven times higher than low-impact vegan or vegetarian menus (Emery and Molidor Reference Emery and Molidor2019).

Regarding estimations for electricity, heating, and catering at the conference venue in Innsbruck, it must be acknowledged that participants also needed electricity, heating, and food when they joined the online conference from home. Yet, it is plausible that energy usage in hotels and at conference locations is higher than the regular energy consumption at a participant’s house or work place.

Regardless of whether onsite emissions are included, the comparison between the virtual and the hypothetical physical event in Innsbruck presents an enormous difference in the carbon footprint. Even the maximum estimation for the online conference is between 94 and 194 times smaller than the estimates for the travel-induced carbon emissions. Using more realistic medium numbers (i.e., best est.) results in an estimate of 780 kg CO₂-eq for the online conference, which is negligible when compared to the 1,250 to 2,575 tons for the physical event.

HYBRID CONFERENCES AS A CARBON-SAVING COMPROMISE?

Although in terms of the carbon footprint, virtual conferences such as the 2020 ECPR GC are clearly preferable compared to physical events, many scholars believe that online meetings lack important features of an in-person meeting. The benefits of direct, face-to-face communication as well as social networking are particularly difficult to realize online. Advances in virtual/augmented reality may bring the meeting experience of online conferences closer to that of a physical event; however, the experience will probably never be exactly the same. Therefore, hybrid conferences with a certain number of participants being physically present while others join virtually may be a compromise. Many universities already acquired the necessary technical equipment during the COVID-19 pandemic for teaching purposes, and conference organizers could resort to this infrastructure for conferences.

This section estimates the extent to which a hybrid conference format could reduce the carbon footprint. To facilitate comparisons, I again used the example of the 2020 ECPR GC with Innsbruck as the conference venue. Estimating emissions of hybrid conferences is based on two factors: (1) the percentage of online participants (i.e., either 10%, 25%, or 50%), and (2) determining which participants join online and which attend in person (i.e., either randomly assigned or those with the highest travel-induced carbon footprints staying at home).

Figure 2 presents the total carbon footprint for these six hypothetical hybrid conference constellations as compared to the numbers for a physical event in Innsbruck and the online event as it actually took place. It is apparent that a hybrid solution is most effective in terms of emission reduction if those attendees with the highest travel-induced carbon footprints joined virtually. With only 10% of participants joining online, the total emissions could be reduced by 51% to 55% if they were coming from the farthest distance from Innsbruck, whereas drawing a 10% random sample of online participants could reduce the emissions by only 8% to 12%. Furthermore, figure 2 shows the significant potential of promoting land-bound travel options, even if they cause longer travel times than flying. For example, if 10% of attendees from far away joined virtually and the other 90% not only accepted up to 5 hours but also up to 20 hours of land-bound travel time, it would result in a reduction of 78% to 79% compared to the baseline estimation (i.e., all attendees in Innsbruck, maximum of 5 hours land-bound travel). For a conference to which only half of the participants (i.e., those living closer to Innsbruck) came in person and the other half joined virtually, a reduction of 1,230 to 2,450 tons CO₂-eq (i.e., 95% to 98% of the baseline estimate) would be possible.

Figure 2

Total Carbon Footprint of the 2020 ECPR GC by Event Mode (Physical/Hybrid/Virtual) and Travel Duration Accepted for Land-Bound Travel (5h/20h)

Notes: Journeys <5 hours/20 hours travel time: by long-distance coach or train; >5 hours/20 hours: by airplane. Range of estimations due to differences in the four emission factors (see table 1). The 10%/25%/50% random participant samples also are based on the 95% confidence interval from simulations of 2,500 draws each.

CONCLUSION—THE FUTURE OF ACADEMIC CONFERENCES: PHYSICAL, ONLINE, OR HYBRID EVENTS?

The COVID-19 pandemic forced many scientific organizations to switch to virtual academic meetings. Using the example of the biggest European Political Science conference, the ECPR GC, this article shows that the carbon footprint of the virtual event was between at least 97 and 200 times smaller than if the meeting had taken place physically in Innsbruck, Austria, as originally intended. Because these are the absolute minimum estimates for the possible reduction, switching to online conferences could be even more beneficial for the environment. These results are relevant not only for this specific case but for all scientific meetings. With more people in the United States traveling by airplane and fewer by train than in Europe, the possible emissions reductions by a virtual meeting such as the 2020 APSA Annual Meeting are likely even higher than the estimates presented in this article.

Although an event held completely online would be most advantageous in terms of a conference’s carbon footprint, there are scholars who still prefer in-person conferences for various reasons (e.g., better option for networking and closer personal contacts).Footnote ⁸ Thus, one option could be to hold conferences only every second year as a physical event and virtually in the alternate years. Yet, as the estimations in this article show, switching to a fully virtual event is not necessarily needed. Hybrid conferences could decrease the carbon footprint in almost the same manner. If one fourth of the attendees join online (primarily those farthest away from the conference venue), a reduction of 67% to 71% of the GHG emissions is well achievable. Furthermore, if the other three fourths would accept travel times of up to 20 hours by coach or train, a hybrid conference could reduce emissions from 86% to 89% compared to an in-person conference.

Of course, decisions about the future format, organization, and design of academic conferences cannot be based only on considerations regarding their carbon footprint. Yet, given the relevance of global warming,Footnote ⁹ it clearly should be an important factor in the decision-making process. Furthermore, I believe that conference organizers should start to see online participation—which this article has shown to hold the most potential for emissions reduction—not only as an imperfect substitution for in-person contacts but also as a solution to other problems that have been neglected too long. Joining a conference virtually, for example, may promote the integration of those who for various reasons could not otherwise attend a physical meeting. In addition to chronically ill people and those with disabilities for whom traveling to conferences might be difficult (De Picker Reference Picker and Marisa2020), this is true for parents and family caregivers who could more easily maintain their daily routines by attending online conferences (Henderson and Moreau Reference Henderson and Moreau2020). Because the child care and family caregiving sectors are still mainly dominated by women, online participation could increase gender diversity in our discipline. Online participation also could promote the integration of scholars from the Global South as well as younger scholars without sufficient funding.

Presumably—at least in the medium to long term—there also will be a decrease in funding options due to the economic consequences of the COVID-19 crisis. Funding agencies may start to question the hitherto existing conference business when they see that virtual conferences work sufficiently well, produce similarly good results as physical events, and are significantly less expensive. The latter point also may be of relevance for conference organizers because holding a virtual conference very well could be economically interesting. That is, even if registration fees must be reduced compared to physical conferences, the much lower spending for an online event could result in significant surpluses. In that way, scientific organizations could help to not only reduce GHG emissions and illustrate their commitment to the fundamental goal of stopping global warming—which is particularly important for the credibility of the entire academia in that regard—but also to introduce a new opportunity of financing its other activities. Taking this step toward more online conferencing requires great courage from organizers because it clearly would be a departure from the well-tried conference format of previous decades. Yet, given the huge acceptance of the 2020 virtual events in our field (e.g., APSA and ECPR), at least political scientists seem to be ready for this transformation.